Phenoic formaldehyde resin (PF) are a varied group of synthetic resins produced through the reaction of phenolic compounds and aldehydes. These resins were first noted in the 1870s, with Bayer creating the first synthesis. Later, through continued study, L.H. Baekeland, an American scientist, created a useful phenolic resin system in 1909. He then started the Bakelite Company, which began the industrial production of phenolic resins. These resins are now common in molding compounds, styling products, insulation, coatings, encapsulation materials, and refractory materials.

1.Synthesis of Phenolic Resins

Phenolic resins are made from a variety of raw materials, resulting in varying types and properties. Phenol-formaldehyde resin is the industrial resin people use most. It is created from phenol and formaldehyde using a two-step process involving addition and polycondensation. Depending on the specific material requirements, the reaction process and rate of the addition and polycondensation reactions can be controlled by varying the synthesis process conditions of phenolic resins to produce resins with varying molecular structures, viscosities, solids contents, and residual carbon content.

2. Classification of Phenolic Resins

The molecular structure of phenolic resins can be changed by controlling the synthesis settings. These settings affect the addition and polycondensation reactions. Based on these molecular structures, phenolic resins can be classified as thermoplastic phenolic resins and thermosetting phenolic resins.

2.1 Thermoplastic Phenolic Resin ( Novolac )

Thermoplastic Phenolic Resin (such as Phenolic Resin 2402) are linear phenolic resins characterized by their straight-chain molecular arrangement.They are primarily produced by reacting excess phenol (P) with formaldehyde (F) under acidic conditions.

Thermoplastic Phenolic Resin are created through a two-stage reaction: first, an addition reaction, then a polycondensation reaction. Because the reaction takes place in an acidic environment, the addition mostly results in monomethylol groups forming at the ortho and para locations on the benzene ring (see Figure 2). The second stage, polycondensation, mainly involves the dehydration of the produced monomethylolphenol with the phenol monomer. Furthermore, under acidic conditions, the rate of the polycondensation reaction is much faster than the addition reaction. Furthermore, the presence of phenol in the reaction system is greater than that of formaldehyde. This causes the hydroxymethyl groups generated during the addition process to rapidly react with the excess phenol in the system to form linear macromolecules, resulting in the absence of active hydroxymethyl functional groups in the reaction product molecules. The structural formula is shown in Figure 4.

2.2 Thermosetting Phenolic Resin ( Resole )

Thermosetting phenolic resin (such as Phenolic resin for electronic materials) is a relatively reactive intermediate product synthesized by reacting for a certain period of time under the action of an alkaline catalyst and heat at a molar ratio of formaldehyde to phenol greater than 1. Therefore, if the synthesis process is not controlled, it can easily react violently, leading to gelation and even cross-linking reactions, ultimately forming insoluble and infusible macromolecules.

The synthesis process of thermosetting phenolic resin is also divided into two steps. The initial stage involves an addition reaction where hydroxymethyl groups are formed on the benzene ring, specifically at the ortho and para positions, leading to the creation of monomethylolphenol. Because the reaction activity of the active hydrogen atoms at the ortho and para positions on the benzene ring is much greater than that of the hydroxyl group on the hydroxymethyl group under alkaline conditions, the resulting hydroxymethyl group is not easily polycondensed.The active hydrogen atoms on the benzene ring can react with more hydroxymethyl groups, leading to the creation of dimethylol and trimethylolphenol. Figure 5 shows this addition reaction. Next, a polycondensation reaction occurs where the polymethylol groups react with active hydrogen atoms on the phenol monomer. This creates a methine bridge, or the hydroxymethyl groups dehydrate to form an ether bond. As this polycondensation keeps happening, it makes a branched resol phenolic resin.

The curing mechanism of thermosetting phenolic resins is quite complex. Currently, the most widely accepted theory is based on the active hydroxymethyl groups present in the molecular structure of thermosetting phenolic resins. During heating, these hydroxymethyl groups react in two ways: with active hydrogen atoms on the benzene ring to form methylene bonds, or with other hydroxymethyl groups to form ether bonds.

3.The Bonding Mechanism of Phenolic Resins as Binders

Four main ideas exist to explain how polymer adhesives stick things together: mechanical interlocking, diffusion, electronic attraction, and adsorption. For phenolic resin systems, mechanical interlocking is key.

The sticking process for phenolic resins occurs in two steps. At the start, the resin goes into all the small holes and uneven areas on the surface of what it's bonding to. For this to happen, the resin needs to be able to wet the surface well. Next, the phenolic resin hardens. During this process, molecules join together to form a network. This lets the resin molecules get stuck in the holes and uneven spots, creating a strong grip that holds the resin and the surface together tightly.

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VAE emulsions are environmentally friendly products. Vinyl groups are embedded in the polyvinyl acetate molecular chain, giving the polymer emulsion a low film-forming temperature and excellent film-forming properties. They exhibit strong adhesion to difficult-to-adhere materials such as PET, PVC, PE, and PP. The polymer film produced is very water and weather resistant. It also holds up well to scrubbing and remains flexible even at low temperatures. The thickness of VAE emulsions is impacted by a number of things. 

1. Effect of Solids Content on Viscosity

We conducted extensive testing on the formulations and process conditions of VAE Emulsion DA-180L and VINNAPAS 400, respectively. The data in the following tables are derived from these tests. The relationship between solids content and viscosity is shown in Table 1.

As shown in Table 1, higher solids content increases viscosity. This is because higher solids content increases the number of colloidal particles in the same emulsion mass, reduces the amount of aqueous phase, and increases the total surface area of the particles. This enhances interparticle interactions and resistance to motion, resulting in higher viscosity.

2. Effect of Protective Colloids on Viscosity

In emulsion polymerization, protective colloids are often used as emulsion stabilizers to improve emulsifier stability and adjust viscosity. The emulsion stability of partially hydrolyzed PVA is also related to the distribution of acetyl groups on the polymer chain. A higher degree of blockiness in the acetyl group distribution results in greater surface activity, better emulsion stability, and smaller and more viscous emulsions. The higher the PVA degree of polymerization, the higher the viscosity of the polyvinyl alcohol aqueous solution before polymerization, and the higher the viscosity of the VAE. The higher the degree of alcoholysis of PVA, the lower the viscosity of the VAE. PVA's protective colloid ability increases with increasing degree of polymerization. Low-degree PVA forms coarser latex particles and has lower viscosity. An increase in the degree of polymerization improves both the protective and dispersing capabilities. To maintain the dispersion and protective properties of PVA during emulsion polymerization, while only adjusting the viscosity, the total amount of PVA is typically kept constant, with only the ratio between the two adjusted. With other conditions remaining unchanged, adding 4.54 kg of PVA Polyvinyl Alcohol 088-20 will increase the viscosity of each batch by 100 mPa·s. Table 2 lists the molecular weight and molecular weight distribution of high- and low-viscosity VAE emulsions.

Table 2 shows that the low-viscosity emulsion has a higher molecular weight, coarser particles, and a wider particle size distribution than the high-viscosity emulsion, resulting in lower viscosity.

3. Effect of Initial Initiator on Viscosity

The initiator has a main influence on the speed of polymerization. The more initiator is used, the faster the polymerization reaction is, and the reaction is difficult to control. After the polymerization conditions and the type of initiator are determined, the amount of initiator can be used to adjust the molecular weight of the polymer. The more initiator is used, the smaller the molecular weight of the polymer is, and the viscosity of the emulsion increases, and vice versa. Among them, the amount of initial initiator (ICAT) added has the greatest impact.

These data clearly show that the more initial initiator is added, the higher the viscosity of the emulsion. This is because the more initial initiator is added, the more difficult the monomer is to react or the reaction rate is slow in the initial stage, and the resulting polymer has a smaller molecular weight, smaller particle size, and higher viscosity.

4. Conclusions

(1) The higher the solid content of the emulsion, the greater the viscosity.

(2) The higher the degree of polymerization of the protective colloid PVA, the greater the viscosity of the emulsion, and vice versa.

(3) The viscosity of the emulsion when PVA is used as a protective colloid is higher than that when cellulose or surfactant is used as a protective colloid.

(4) With the same degree of polymerization, the higher the degree of alcoholysis, the lower the viscosity of the emulsion.

(5) The more initial initiator and total amount of initiator added, the higher the viscosity of the emulsion.

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You encounter Polyvinyl Alcohol every day, whether you know it or not. Manufacturers rely on this material for its water solubility, biodegradability, and film-forming ability. Industries such as textiles, packaging, paper, and construction depend on its unique properties to create safer, more sustainable products.

1. What Is Polyvinyl Alcohol?

You may wonder what Polyvinyl Alcohol is. This material is a synthetic polymer created through the hydrolysis of polyvinyl acetate. Its molecular structure features repeating units of [CH2-CHOH]n. You will find Polyvinyl Alcohol in many products, including well-known grades like Mowiol 10-98, shuangxin pva, and PVA 205.

Primary chemical characteristics include:

• Water solubility from hydroxyl groups
• Thermal stability with a melting point near 230°C
• Good mechanical strength and flexibility

Common grades you might encounter:

• PVA 2488, PVA 1788, PVA 2088
• Fully hydrolyzed and partially hydrolyzed types

2. How PVA Is Made?

You can understand the production of Polyvinyl Alcohol by looking at its industrial process. Manufacturers start with polyvinyl acetate and use hydrolysis to convert acetoxy groups into hydroxyl groups. This step creates different grades of PVA.

You will see that the process involves dissolving polyvinyl acetate in alcohol and using an alkaline catalyst. Hydrolysis removes acetate groups but keeps the polymer structure intact.

3. Is PVA a Plastic?

You might ask if Polyvinyl Alcohol is a plastic. PVA is a synthetic polymer made from petroleum sources. Many people associate it with plastics because of its origin and properties. Some definitions include PVA as a plastic, but it differs from conventional plastics in several ways.

You will notice that Polyvinyl Alcohol offers high tensile strength, flexibility, and excellent film-forming abilities. These features set it apart from other synthetic polymers.

4. Properties and Industrial Uses

You will notice that Polyvinyl Alcohol stands out because of its unique combination of properties. This material dissolves in water at any concentration, which makes it highly versatile for many applications. However, as you increase the amount of PVA in water, the solution becomes thicker and harder to handle.

• Polyvinyl Alcohol forms solutions in water at any concentration.
• Higher concentrations lead to increased viscosity, which can limit practical use.

You can rely on PVA for its strong adhesive qualities, even though its adhesive strength is lower than some other common adhesives. Here is a comparison of adhesive strength:

You will also find that PVA creates clear, flexible films. These films offer excellent barrier properties and help improve the durability of products. Another important property is biodegradability. PVA can break down naturally, which supports eco-friendly practices.

5. Why PVA Is Essential?

You might wonder why Polyvinyl Alcohol is so important in modern industry. Its unique properties allow you to solve challenges in manufacturing, packaging, and product design. PVA’s water solubility and film-forming ability make it a top choice for eco-friendly packaging. Its adhesive strength and flexibility support high-quality paper, textiles, and construction materials.

• PVA is biodegradable, which helps reduce plastic waste in landfills and water bodies.
• Water-soluble films made from PVA provide an eco-friendly option for packaging.
• PVA coatings improve product integrity and barrier properties.
• Edible coatings made from PVA extend the shelf life of fruits and vegetables.

You will find that PVA is marketed as an eco-friendly alternative because of its water solubility and potential for biodegradability. Many industries choose PVA to support sustainable practices and reduce their environmental impact. As you look for ways to make products safer and more sustainable, PVA remains a key material in your toolkit.

6. Safety and Environmental Impact

You can feel confident using Polyvinyl Alcohol in many settings because it has a strong safety profile. The FDA approves it for food packaging and pharmaceutical capsules, which shows its suitability for direct contact with humans. PVA is non-toxic and water-soluble, making it less harmful than many traditional polymers. You may notice some risks in industrial environments. Prolonged or repeated skin contact with PVA adhesives can cause skin irritation or dermatitis, especially if you have sensitive skin. Inhaling dust or fumes during manufacturing may lead to respiratory discomfort. You can reduce these risks by wearing gloves and masks and ensuring proper ventilation.

• PVA is FDA-approved for food and pharmaceutical use.
• Non-toxic and water-soluble.
• Skin irritation or respiratory discomfort may occur with direct exposure.

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Aluminum nitride (AlN) ceramici s an advanced ceramic material serving as a key thermal management solution in the semiconductor and 5G industries. Its exceptional thermal conductivity (170-230 W/mK) and reliable electrical insulation properties heavily depend on one core characteristic: sintering activity. Simply put, sintering activity determines whether high-purity AlN powder can achieve high densification efficiently at elevated temperatures to form high-performance ceramics for electronic packaging, heat spreaders, and substrate applications.

What is Sintering Activity?

Sintering activity refers to the ability of a ceramic powder to form a dense structure during heat treatment. Powder with high activity enables low-temperature sintering, achieving high density in shorter timeframes, significantly reducing production costs while enhancing thermal performance and mechanical reliability.

Three Key Factors Influencing Sintering Activity

1. Powder Particle Size

Fine powder with submicron particles provides larger specific surface area and higher surface energy, resulting in stronger sintering drive and improved microstructure development.

2. Oxygen Content Control

Excessive oxygen content leads to alumina formation, creating interfacial barriers that degrade thermal conductivity and hinder densification process. Maintaining low oxygen levels is critical for high thermal conductivity AlN.

3. Sintering Additives

Yttria (Y₂O₃) additives react with surface oxides to form liquid phase sintering, enhancing mass transport and pore elimination. This enables pressureless sintering of high-density AlN ceramics with optimized grain boundary engineering.

How to Optimize Sintering?

1、Use high-purity AlN powder with controlled particle size distribution

2、Implement atmospheric sintering under nitrogen environment

3、Apply sintering aids for microstructure control

4、Utilize non-oxide additives for thermal conductivity enhancement

5、Optimize sintering profile for cost-effective production

Conclusion

Sintering activity is a critical material property determining the end-performance of AlN ceramics in power electronics, LED packaging, and RF applications. Mastery of sintering technology enables manufacturers to produce high-thermal-conductivity substrates with superior mechanical strength and reliability performance, positioning AlN as the material of choice for next-generation thermal management solutions.

About Xiamen Juci Technology Co., LTD

Xiamen Juci Technology Co., Ltd. is a leading Chinese manufacturer of aluminum nitride (AlN) powder, utilizing the carbothermal reduction method for its production. The aluminum nitride powder produced through this process exhibits exceptionally high sintering activity and ultra-high purity. Such powder enables the fabrication of highly dense aluminum nitride ceramics, providing superior thermal management solutions for 5G communications, semiconductors, and other advanced industries.

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Xiamen Juci Technology Co., Ltd.

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In the grand stage of pipeline fluid control, the control valve is undoubtedly the "leading role". Today, let's get to know this "big shot" that can precisely regulate the fluid.

What is a control valve?

A control valve is a type of valve used to regulate parameters such as the flow rate, pressure, and temperature of the fluid in a pipeline. It is like an intelligent "traffic policeman". According to the needs of the system, it can flexibly adjust the valve opening, thereby controlling the flow state of the fluid. By receiving signals from various sensors, the control valve can react in real time to ensure that the fluid always operates according to the predetermined parameters, providing a strong guarantee for the stable operation of the entire system.

The Diverse Types of Control Valves

Pneumatic Control Valve: Using compressed air as the power source, it drives the valve to act by controlling the air pressure. It has a fast response speed and high control precision, just like an agile "athlete". It is often used in industrial automation production lines with high requirements for control precision and fast response speed. For example, in the feed control of the reactor in chemical production, it can accurately regulate the material flow rate to ensure the stability of the production process.

Electric Control Valve: Using an electric motor as the driving device, it controls the opening and closing of the valve through electrical signals. It is easy to operate and is convenient for realizing remote control, just like a "commander" that can be remotely controlled. In the building automation system, the electric control valve is often used for the temperature regulation of the air conditioning system. According to the changes in indoor and outdoor temperatures, it can automatically adjust the flow rate of chilled water or hot water to create a comfortable indoor environment for people.

Self-operated Control Valve: It does not require external energy and relies on the energy of the fluid itself to achieve regulation. It is like a self-sufficient "lone ranger" that can automatically adjust the valve opening according to parameters such as the pressure and temperature of the fluid in the pipeline. For example, in the heating system, the self-operated control valve can automatically adjust the flow rate of steam or hot water according to the needs of the user end to achieve energy-saving and efficient heating.

The Application Scenarios of Control Valves

Petrochemical Industry: In processes such as petroleum refining and chemical production, it is necessary to precisely control the flow rate and pressure of various fluids. The control valve can ensure that chemical reactions occur under appropriate conditions and prevent safety accidents caused by the out-of-control of fluid parameters. It is the "safety guardian" of chemical production.

Power Industry: In thermal power plants, the control valve is used to control the flow rate and pressure of steam, regulate the combustion efficiency of the boiler, and ensure the stable operation of the power generation equipment. It is like the "power regulator" of the power plant, contributing to the stable supply of electricity.

Environmental Protection and Water Treatment: In sewage treatment plants, the control valve can adjust the dosage of the chemical dosing device according to the changes in the flow rate and water quality of the sewage, and control the flow velocity of the sewage in each treatment process to ensure that the sewage treatment effect meets the standards. It is the "green facilitator" of environmental protection undertakings.

Plug Valve: The Versatile Expert in Pipeline Fluid Control

In the vast network of pipeline systems, the plug valve is indeed a capable expert in controlling fluids. Its core component is a rotatable plug, which is just like a flexible "rotary switch". There are through - holes of different shapes distributed on the plug. As the plug rotates, the through - holes align with or stagger from the pipeline, thus ingeniously realizing the on - off control and flow regulation of the fluid. This process is like equipping the pipeline with a magical "rotary key", which can easily control the flow direction and flow rate of the fluid.

The family of plug valves is rich and diverse in types. The ordinary plug valve is the most basic type, with a simple structure and relatively low cost. Its plug is usually cylindrical, and the rotation operation is very convenient. This kind of plug valve is suitable for occasions with low requirements for sealing performance and clean media, such as some simple water pipeline systems. In these scenarios, it is like a simple and unadorned "basic guard", silently safeguarding the normal flow of ordinary fluids. Although it seems ordinary, it is indispensable.

The oil - sealed plug valve is an upgraded version of the ordinary plug valve, with an additional oil - sealing device. This layer of oil seal is just like putting on a solid "sealing armor" for the plug, greatly improving the sealing performance of the valve. Therefore, it is often used in occasions where high - sealing - performance fluids such as oil and natural gas are transported. In these key transportation processes, the oil - sealed plug valve is like a meticulous and rigorous "sealing guard", always on high alert to ensure the safe and leak - free transportation of energy, providing a solid guarantee for the stable operation of industrial production and energy supply.

The plug - ball valve combines the advantages of both the plug valve and the ball valve, with a more ingenious plug design. It not only has good sealing performance to effectively prevent fluid leakage but also has the characteristic of fast opening and closing. In some industrial scenarios with extremely high requirements for fluid - cutting speed, such as emergency - cutting devices in chemical production, the plug - ball valve is like an agile and efficient "emergency vanguard". In critical moments, it can respond quickly and cut off the fluid rapidly to avoid potential dangers and losses, ensuring the safety and stability of the production process.

In terms of urban water supply and drainage systems, the plug valve plays an important role in water supply and drainage pipe networks. It can be opened and closed quickly, providing great convenience for pipeline maintenance and repair work, and effectively ensuring the stable operation of the urban water system. It can be called the "water - flow commander" in the field of water supply and drainage. Whether it is the daily water - supply scheduling or the emergency treatment in case of sudden situations, the plug valve can play a key role to ensure the unobstructed "lifeline" of the city.

In the petrochemical industry, the plug valve is widely used due to its good sealing performance and excellent corrosion resistance. In this challenging field, whether it is transporting highly corrosive chemical raw materials or handling flammable and explosive petroleum products, the plug valve can give full play to its own advantages. It is like a loyal and reliable "safety guardian", always sticking to its post to ensure the safety and stability of the production process, escorting the vigorous development of the petrochemical industry.

In the field of gas transportation, for gas, a flammable and explosive fluid, the sealing performance is undoubtedly crucial. The unique oil - seal design of the plug valve makes it perform excellently in gas - transportation pipelines, just like a trustworthy "gas guard", safeguarding the gas - using safety of every household. It not only ensures the stable supply of gas but also provides a reliable safety guarantee for people's daily lives, allowing people to use gas resources with peace of mind.

Although the plug valve may not be eye - catching in appearance, with its unique structure and diverse performance, it plays an irreplaceable and important role in the field of pipeline fluid control. It is like a silent "rotary - core hero", providing all - round escort for our production and life in its own unique way, leaving a solid and reliable mark in all aspects of industrial production and daily life.

A seemingly minor material challenge is now bottlenecking progress across the electronics industry: thermal management. As traditional solutions like aluminum oxide (Al₂O₃) and silicon nitride (Si₃N₄) struggle to meet the heat dissipation demands of modern devices, aluminum nitride (AlN) has emerged as the critical solution. Its unique properties are driving adoption across multiple high-tech sectors—but what makes AlN the material of the moment?

1. Addressing High-Power Density Challenges

5G/6G Communications: Base station power amplifiers (PAs) and RF modules require unprecedented thermal performance. AlN substrates deliver thermal conductivity (200–230 W/mK), dwarfing Al₂O₃ (30 W/mK).

Third-Generation Semiconductors: For SiC/GaN devices operating above 200°C, AlN’s thermal expansion coefficient (4.5×10⁻⁶/K) provides near-perfect semiconductor matching, minimizing thermal stress failures.

Advanced Packaging: In 2.5D/3D architectures, AlN interposers solve heat dissipation challenges in stacked chip designs.

2. New Energy and EV Applications

Power Batteries: AlN serves as an insulated thermal substrate in battery management systems (BMS), offering high-voltage resistance (>800V) and flame retardancy.

Automotive Electronics: Replacing Al-SiC composites, AlN substrates now cool IGBT modules and radar systems in electric vehicles.

3. Regulatory and Environmental Drivers

BeO Replacement: The EU’s RoHS directive has phased out toxic beryllium oxide (BeO), leaving AlN as the only safe, high-thermal-conductivity alternative.

Carbon Neutrality: Surging demand for clean energy equipment—photovoltaic inverters, wind power converters—is accelerating AlN adoption.

About Xiamen Juci Technology Co., LTD

Xiamen Juci Technology Co., Ltd. is China's leading manufacturer of aluminum nitride (AlN) powder by production volume. Our high-purity aluminum nitride powder and customized AlN ceramic products deliver superior thermal conductivity and cost-effective performance, making them ideal for advanced thermal management applications.

We specialize in innovative thermal solutions tailored for industries such as 5G communications, semiconductors, new energy, and aerospace, helping clients achieve optimal heat dissipation and system reliability.

Media Contact:
Xiamen Juci Technology Co., Ltd.

Phone: +86 592 7080230
Email: miki_huang@chinajuci.com

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Bismaleimide resin (BMI Resin or Bismaleimide) is a high-performance thermosetting polymer. Compared to conventional epoxy resins, it offers superior high-temperature resistance, mechanical strength, and electrical insulation properties, making it widely used in aerospace, automotive electronics, advanced composites, and other fields.

BMI Resin's molecular structure contains maleimide groups, which form a highly cross-linked network through addition or free radical polymerization. This ensures stable performance in environments with continuous operating temperatures of 250–300°C, maintaining strength and reliability.

Bismaleimide Series